Bundles of wires carrying multiple signals are usually connected to other similar bundles or interfaced to devices such as instruments and control mechanisms through the use of electrical connectors into which contacts corresponding to the individual wires of the bundles are assembled. The connectors allow leads from the wires to be brought into an orderly mating relationship with conductive leads from other wire bundles, instruments, or control mechanisms.
It is conventional for a connector to comprise a pair of cylindrical shells which are adapted for fitting together in a single prescribed manner. Each such shell includes a contact receiving insert. Each insert is made of a dielectric material and is in the form of a plate having an inner surface which is intended to confront the other insert within the connector and an opposite outer surface which is parallel to the inner surface. Numerous holes penetrate the inserts opening at their opposite ends to the inner and outer surfaces of the inserts.
A wire is prepared for attachment to the connector by stripping the dielectric sleeve from the end of the wire so as to expose its conductive core and crimping a contact onto the conductor. This contact may be in the form of either a pin or a pin receiving receptacle. The contact is introduced into a hole in an insert by way of the outer surface thereof and, in the case of a pin, projects beyond the inner surface of the insert. When all the wires have been attached to their respective inserts and the inserts are brought together, the contacts that are received in the holes of one insert are physically engaged by the contacts that are received in the holes of the matching insert within the connector.
In many cases, the number of holes within connectors turns out to be greater than the number of wires to be attached thereto. For many applications, the connector must be sealed by filling the unused holes with filler elements of a non-conductive material, e.g. to prevent unwanted air leaks.
When attaching a breakout or "bundle" of wires from a wiring harness to a particular connector, it is necessary to insure that the contacts and filler elements are located in the proper holes of the insert since otherwise the right circuits will not be completed when it is coupled to its mating insert within the connector.
One method of insuring that the contacts and filler elements are positioned in the proper holes involves the use of a plug map. Each hole in the insert is numbered and each wire is labeled to carry an identifying number specific to the wire. The plug map correlates the wire numbers with the hole numbers. The user selects a wire for attachment to the connector, reads the wire number, consults the plug map to find the number of the hole associated with the selected wire, scans the plug to locate that hole, and inserts the contact of the selected wire into the hole. Therefore, use of a plug map is subject to a disadvantage in that it involves carrying out a random search of the plug map for the wire number and then searching the connector itself to find the corresponding hole. Consequently, attaching the wires to the connector using a plug map in this manner is time consuming and, furthermore, is subject to error in that it is easy to confuse the wire numbers on the plug map and to mistake one hole location for another.
In an automated robotic connector assembly machine, the operations of wire stripping, contact crimping and insertion are performed automatically. However, the wires and filler elements must first be dressed into predetermined locations in a fixture associated with the assembly machine. Therefore, this technique involves a high capital cost while still involving a substantial amount of manual labor.
In a cable scan system, the operator touches the contact of a selected wire to an electrode which receives a signal over the wire. This signal represents the wire number in encoded form, and is decoded and applied to an electronic lookup table. The lookup table contains the plug map and provides the operator with the hole number without its being necessary for the operator to scan a plug map. However, this system is only applicable when the opposite end of the selected wire is connected to a signal source, i.e., has already been attached to its own connector, and does not relieve the operator of the burden of searching the insert plate for the hole having the number provided by the lookup table. Further, this system is not in any way helpful in assembling non-conductive filler elements into the connector.
Several methods have been proposed for assisting in identifying the correct hole for receiving a particular contact or filler element. For example, U. S. Pat. No. 3,706,134 (Sweeney et al) addresses the problem of locating the correct hole number when the density of holes is high and the numbers imprinted on the connector are small. The connector is fitted over an array of optical fibers such that the fibers are positioned beneath specific holes. An input panel which constitutes an enlarged replica of the outer surface of the connector is formed with an aperture for each hole in the connector. The optical fibers couple the apertures in the panel with the corresponding holes in the connector. Therefore, when a light source is placed in an aperture of the panel, light is emitted from the corresponding hole in the connector. The operator is thereby able to identify the holes by reference to the much larger panel, which facilitates correct identification of the holes. However, this does not alleviate the difficulty associated with searching a plug map, and moreover because connector blocks are of significant depth and the holes are generally quite narrow, it can be difficult to spot which hole is in fact emitting light.
In U. S. Pat. No. 4,727,637 (Buckwitz et al) a method and apparatus is disclosed for assisting in the insertion of electrical contacts into connectors by visually identifying the locations of specific holes within electrical connectors. A fiber optic rod attached at one end to a light source is adapted for being directed into the holes to be identified so that the other end of the rod projects above the holes and can be easily spotted by an operator of the apparatus. In operation, the fiber optic rod is advanced into and retracted out of the holes within the connector corresponding to specific wires selected by the operator as the operator one by one either inserts electrical contacts for the wires or filler rods into each of the holes. The system is effective but still relies on considerable manual effort in installing filler rods which may be numerous, resulting in many time consuming steps.
It is therefore an object of the present invention to provide an improved system for assembling electrical connectors which includes a mechanism for automatically installing filler elements into the connector without manual assistance.
It is another object of the present invention to provide an improved system for assembling electrical connectors which conveniently positions electrical connectors for rapid operation with respect to insertion of electrical contacts and installation of filler rods.
It is a further object of the present invention to provide an improved system for assembling electrical connectors which is effective in providing increased operational efficiency in the assembly process.